Beta blockers reduce blood pressure by blocking the effects of adrenaline -- also known as the hormone epinephrine -- which in turn causes the heart to beat more slowly with less force, according to The Mayo Clinic. The pills can also boost blood flow by opening up blood vessels.

"With the number of people with Alzheimer's disease expected to grow significantly as our population ages, it is increasingly important to identify factors that could delay or prevent the disease," study author Dr. Lon White, a geriatric medicine researcher at the Pacific Health Research and Education Institute in Honolulu, said in a written statement. "These results are exciting, especially since beta blockers are a common treatment for high blood pressure."

White's study involved 774 elderly Japanese-American men who were enrolled in the Honolulu-Asia Aging Study, a long-running study that kicked off in 1991 and included autopsies after subject's deaths.

Researchers found 610 of the men had high blood pressure or were treated with medication for high blood pressure. Of the 350 men who were receiving treatment, 15 took a beta blocker, 18 took beta blockers plus one or more other medications, while the rest took other blood pressure drugs.

Men who took beta blockers as their only medication had fewer brain abnormalities compared to those who had not been treated for hypertension, or those who had received other blood pressure medications. Brain abnormalities included lesions called "microinfarcts" which are multiple, tiny strokes that typically go unrecognized, in addition to lesions indicative of Alzheimer's disease.

Those who received beta blockers plus other medications also showed reductions in brain abnormalities, but not as many as the group taking beta blockers alone. All types of blood pressure treatments were better than no treatment at all, according to the researchers.

"What we're seeing is another advantage of treating hypertension,'' White told USA Today. "It reduces heart disease and stroke, but we're saying it looks like it can also reduce all kinds of dementia."

The study was released Jan. 8 on the American Academy of Neurology's website but will be presented at the academy's annual meeting in March.

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Commenting on the study Heather Snyder, senior associate director of medical and scientific relations for the Alzheimer's Association, told HealthDay the study was interesting but had some limitations, including the fact tha some people with brain lesions don't experience cognitive changes such as memory loss.

"It's a small study," said Snyder. "I would agree it is premature to draw conclusions about treatment."

About 5.4 million Americans are living with Alzheimer's disease -- that's about one in eight older adults. It is the sixth-leading cause of death in the U.S., but the only cause of death that can't be prevented, cured and slowed, according to the Alzheimer's Association.